sh: fixup many sparse errors.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/drivers/serial/sh-sci.c b/drivers/serial/sh-sci.c
index 3df2aae..f5aebc9 100644
--- a/drivers/serial/sh-sci.c
+++ b/drivers/serial/sh-sci.c
@@ -1113,7 +1113,7 @@
 		case PORT_IRDA: return "irda";
 	}
 
-	return 0;
+	return NULL;
 }
 
 static void sci_release_port(struct uart_port *port)